"We now estimate that if Congress does not raise or suspend the debt ceiling by October 18, the US Treasury may exhaust its special measures," Janet Yellen, the US Treasury secretary, said in a letter to Congress.

"at that time, we expect the Treasury's resources to be very limited and will soon be exhausted," Ms. Yellen said. "after that date, it is uncertain whether we will be able to continue to live up to all the country's commitments."